The Nautical Almanac # 51 --- Altair, the Star of the Eagle

 

The Fifty-First star in the Nautical Almanac, like Vega and Nunki, received its name from the ancient Sumerians. Inanna was the Sumerian goddess of war. The sister of Enki and Enli, she was frequently portrayed either with or as a hunting eagle, and this is how she appears in our heavens to this day. Her star was her consort, a god named Zababba, and he was ever after known as the Star of the Eagle. Unlike Nunki (which never became the Greek Pelagus) the name Zababba was supplanted by its Greek translation, Altair. 

Altair (or to give it its scientific name Alpha Aquilae) is the brightest star in the constellation of Aquila The Eagle. The word "aquila" ("eagle") is interesting, for at its root it makes reference to water ("aqua"). In ancient Mesopotamia eagles hunted along the riverbanks of the Tigris and the Euphrates and were considered water birds. In the earliest days, Altair was the patron star of the Mesopotamian city of Kis; later, Altair became the star of the Roman Empire. Many modern astrologers believe Altair is the star of the United States.

Altair is one of the stars of the Summer Triangle. Altair is the boy in the Chinese legend of the Triangle, in which he and the girl (Vega), lovers, are kept apart by Deneb, the girl's father. 

To the Greeks, Aquila, with its star, was the eagle who ate Prometheus' liver every day in punishment for bringing light to Man. In almost all cultures, including the Australian Aboriginal, Aquila / Altair is seen as an eagle, but among some South Pacific islanders it is a flying fish or giant fish. 

Altair is a bluish-white First Magnitude Main Sequence star. It is only 16 light years from Earth, making it quite noticeable in our night sky. It has a mass of 1.8 times that of the Sun and a radius of 1.6 times the Sun. A variable star, it is about 10 to 11 times as luminous as our Sun. It burns at 14,900 degrees Fahrenheit, hot for its size. Estimates of its age range from "a few hundred million years" to 1.2 billion years, and it is not expected to live more than a billion more. Altair rotates at 471,600 miles per hour, completing a full rotation in just ten hours. The star is spinning at more than 90% of its maximum speed and is close to being torn apart by centrifugal forces. The star, as can be seen in the photo, is extremely oblate.

Since it is close and bright Altair has been studied extensively. It was the first star (besides the Sun) to have its surface photographed. Spectroscopic analysis tells us that Altair contains an unusual amount of iron and other heavy metals.It also emits X-Rays. It has a planet forming dust cloud around it, which seems to be thinning out. That may mean it has recently-formed planets. Since its "Goldilocks Zone" lies beyond the dust cloud, the possibility exists that Altair has a young earth-like (or at least Earth-sized) planet around it. 

Altair is very popular in science fiction. It is the star of the "Forbidden Planet" in that 1956 eponymously-named film, and has been referenced in Asimov's "Foundation" series, in other books and films, and frequently on Star Trek. It is also popular with technologists: Series of rockets have been named Altair and the first marketed home computer was dubbed the Altair 8800.

Anne Francis as Altaira Morbius, the heroine of 1956's "Forbidden Planet"